[linux.git] / net / sctp / tsnmap.c

/* SCTP kernel reference Implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 Intel Corp.
 *
 * This file is part of the SCTP kernel reference Implementation
 *
 * These functions manipulate sctp tsn mapping array.
 *
 * The SCTP reference implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * The SCTP reference implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <[email protected]>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <[email protected]>
 *    Jon Grimm             <[email protected]>
 *    Karl Knutson          <[email protected]>
 *    Sridhar Samudrala     <[email protected]>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#include <linux/types.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

static void sctp_tsnmap_update(struct sctp_tsnmap *map);
static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
				     __u16 len, __u16 base,
				     int *started, __u16 *start,
				     int *ended, __u16 *end);

/* Initialize a block of memory as a tsnmap.  */
struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
				     __u32 initial_tsn)
{
	map->tsn_map = map->raw_map;
	map->overflow_map = map->tsn_map + len;
	map->len = len;

	/* Clear out a TSN ack status.  */
	memset(map->tsn_map, 0x00, map->len + map->len);

	/* Keep track of TSNs represented by tsn_map.  */
	map->base_tsn = initial_tsn;
	map->overflow_tsn = initial_tsn + map->len;
	map->cumulative_tsn_ack_point = initial_tsn - 1;
	map->max_tsn_seen = map->cumulative_tsn_ack_point;
	map->malloced = 0;
	map->num_dup_tsns = 0;

	return map;
}

/* Test the tracking state of this TSN.
 * Returns:
 *   0 if the TSN has not yet been seen
 *  >0 if the TSN has been seen (duplicate)
 *  <0 if the TSN is invalid (too large to track)
 */
int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
{
	__s32 gap;
	int dup;

	/* Calculate the index into the mapping arrays.  */
	gap = tsn - map->base_tsn;

	/* Verify that we can hold this TSN.  */
	if (gap >= (/* base */ map->len + /* overflow */ map->len)) {
		dup = -1;
		goto out;
	}

	/* Honk if we've already seen this TSN.
	 * We have three cases:
	 *	1. The TSN is ancient or belongs to a previous tsn_map.
	 *	2. The TSN is already marked in the tsn_map.
	 *	3. The TSN is already marked in the tsn_map_overflow.
	 */
	if (gap < 0 ||
	    (gap < map->len && map->tsn_map[gap]) ||
	    (gap >= map->len && map->overflow_map[gap - map->len]))
		dup = 1;
	else
		dup = 0;

out:
	return dup;
}


/* Mark this TSN as seen.  */
void sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
{
	__s32 gap;

	/* Vacuously mark any TSN which precedes the map base or
	 * exceeds the end of the map.
	 */
	if (TSN_lt(tsn, map->base_tsn))
		return;
	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
		return;

	/* Bump the max.  */
	if (TSN_lt(map->max_tsn_seen, tsn))
		map->max_tsn_seen = tsn;

	/* Assert: TSN is in range.  */
	gap = tsn - map->base_tsn;

	/* Mark the TSN as received.  */
	if (gap < map->len)
		map->tsn_map[gap]++;
	else
		map->overflow_map[gap - map->len]++;

	/* Go fixup any internal TSN mapping variables including
	 * cumulative_tsn_ack_point.
	 */
	sctp_tsnmap_update(map);
}


/* Initialize a Gap Ack Block iterator from memory being provided.  */
SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
				       struct sctp_tsnmap_iter *iter)
{
	/* Only start looking one past the Cumulative TSN Ack Point.  */
	iter->start = map->cumulative_tsn_ack_point + 1;
}

/* Get the next Gap Ack Blocks. Returns 0 if there was not another block
 * to get.
 */
SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
					 struct sctp_tsnmap_iter *iter,
					 __u16 *start, __u16 *end)
{
	int started, ended;
	__u16 _start, _end, offset;

	/* We haven't found a gap yet.  */
	started = ended = 0;

	/* If there are no more gap acks possible, get out fast.  */
	if (TSN_lte(map->max_tsn_seen, iter->start))
		return 0;

	/* Search the first mapping array.  */
	if (iter->start - map->base_tsn < map->len) {

		offset = iter->start - map->base_tsn;
		sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 0,
					 &started, &_start, &ended, &_end);
	}

	/* Do we need to check the overflow map? */
	if (!ended) {
		/* Fix up where we'd like to start searching in the
		 * overflow map.
		 */
		if (iter->start - map->base_tsn < map->len)
			offset = 0;
		else
			offset = iter->start - map->base_tsn - map->len;

		/* Search the overflow map.  */
		sctp_tsnmap_find_gap_ack(map->overflow_map,
					 offset,
					 map->len,
					 map->len,
					 &started, &_start,
					 &ended, &_end);
	}

	/* The Gap Ack Block happens to end at the end of the
	 * overflow map.
	 */
	if (started && !ended) {
		ended++;
		_end = map->len + map->len - 1;
	}

	/* If we found a Gap Ack Block, return the start and end and
	 * bump the iterator forward.
	 */
	if (ended) {
		/* Fix up the start and end based on the
		 * Cumulative TSN Ack offset into the map.
		 */
		int gap = map->cumulative_tsn_ack_point -
			map->base_tsn;

		*start = _start - gap;
		*end = _end - gap;

		/* Move the iterator forward.  */
		iter->start = map->cumulative_tsn_ack_point + *end + 1;
	}

	return ended;
}

/* Mark this and any lower TSN as seen.  */
void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
{
	__s32 gap;

	/* Vacuously mark any TSN which precedes the map base or
	 * exceeds the end of the map.
	 */
	if (TSN_lt(tsn, map->base_tsn))
		return;
	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
		return;

	/* Bump the max.  */
	if (TSN_lt(map->max_tsn_seen, tsn))
		map->max_tsn_seen = tsn;

	/* Assert: TSN is in range.  */
	gap = tsn - map->base_tsn + 1;

	/* Mark the TSNs as received.  */
	if (gap <= map->len)
		memset(map->tsn_map, 0x01, gap);
	else {
		memset(map->tsn_map, 0x01, map->len);
		memset(map->overflow_map, 0x01, (gap - map->len));
	}

	/* Go fixup any internal TSN mapping variables including
	 * cumulative_tsn_ack_point.
	 */
	sctp_tsnmap_update(map);
}

/********************************************************************
 * 2nd Level Abstractions
 ********************************************************************/

/* This private helper function updates the tsnmap buffers and
 * the Cumulative TSN Ack Point.
 */
static void sctp_tsnmap_update(struct sctp_tsnmap *map)
{
	__u32 ctsn;

	ctsn = map->cumulative_tsn_ack_point;
	do {
		ctsn++;
		if (ctsn == map->overflow_tsn) {
			/* Now tsn_map must have been all '1's,
			 * so we swap the map and check the overflow table
			 */
        		__u8 *tmp = map->tsn_map;
			memset(tmp, 0, map->len);
			map->tsn_map = map->overflow_map;
			map->overflow_map = tmp;

			/* Update the tsn_map boundaries.  */
			map->base_tsn += map->len;
			map->overflow_tsn += map->len;
		}
	} while (map->tsn_map[ctsn - map->base_tsn]);

	map->cumulative_tsn_ack_point = ctsn - 1; /* Back up one. */
}

/* How many data chunks  are we missing from our peer?
 */
__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
{
	__u32 cum_tsn = map->cumulative_tsn_ack_point;
	__u32 max_tsn = map->max_tsn_seen;
	__u32 base_tsn = map->base_tsn;
	__u16 pending_data;
	__s32 gap, start, end, i;

	pending_data = max_tsn - cum_tsn;
	gap = max_tsn - base_tsn;

	if (gap <= 0 || gap >= (map->len + map->len))
		goto out;

	start = ((cum_tsn >= base_tsn) ? (cum_tsn - base_tsn + 1) : 0);
	end = ((gap > map->len ) ? map->len : gap + 1);

	for (i = start; i < end; i++) {
		if (map->tsn_map[i])
			pending_data--;
	}

	if (gap >= map->len) {
		start = 0;
		end = gap - map->len + 1;
		for (i = start; i < end; i++) {
			if (map->overflow_map[i])
				pending_data--;
		}
	}

out:
	return pending_data;
}

/* This is a private helper for finding Gap Ack Blocks.  It searches a
 * single array for the start and end of a Gap Ack Block.
 *
 * The flags "started" and "ended" tell is if we found the beginning
 * or (respectively) the end of a Gap Ack Block.
 */
static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
				     __u16 len, __u16 base,
				     int *started, __u16 *start,
				     int *ended, __u16 *end)
{
	int i = off;

	/* Look through the entire array, but break out
	 * early if we have found the end of the Gap Ack Block.
	 */

	/* Also, stop looking past the maximum TSN seen. */

	/* Look for the start. */
	if (!(*started)) {
		for (; i < len; i++) {
			if (map[i]) {
				(*started)++;
				*start = base + i;
				break;
			}
		}
	}

	/* Look for the end.  */
	if (*started) {
		/* We have found the start, let's find the
		 * end.  If we find the end, break out.
		 */
		for (; i < len; i++) {
			if (!map[i]) {
				(*ended)++;
				*end = base + i - 1;
				break;
			}
		}
	}
}

/* Renege that we have seen a TSN.  */
void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
{
	__s32 gap;

	if (TSN_lt(tsn, map->base_tsn))
		return;
	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
		return;

	/* Assert: TSN is in range.  */
	gap = tsn - map->base_tsn;

	/* Pretend we never saw the TSN.  */
	if (gap < map->len)
		map->tsn_map[gap] = 0;
	else
		map->overflow_map[gap - map->len] = 0;
}

/* How many gap ack blocks do we have recorded? */
__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map)
{
	struct sctp_tsnmap_iter iter;
	int gabs = 0;

	/* Refresh the gap ack information. */
	if (sctp_tsnmap_has_gap(map)) {
		sctp_tsnmap_iter_init(map, &iter);
		while (sctp_tsnmap_next_gap_ack(map, &iter,
						&map->gabs[gabs].start,
						&map->gabs[gabs].end)) {

			map->gabs[gabs].start = htons(map->gabs[gabs].start);
			map->gabs[gabs].end = htons(map->gabs[gabs].end);
			gabs++;
			if (gabs >= SCTP_MAX_GABS)
				break;
		}
	}
	return gabs;
}
Commit	Line	Data
1da177e4 LT	1	/* SCTP kernel reference Implementation
	2	* (C) Copyright IBM Corp. 2001, 2004
	3	* Copyright (c) 1999-2000 Cisco, Inc.
	4	* Copyright (c) 1999-2001 Motorola, Inc.
	5	* Copyright (c) 2001 Intel Corp.
	6	*
	7	* This file is part of the SCTP kernel reference Implementation
	8	*
	9	* These functions manipulate sctp tsn mapping array.
	10	*
	11	* The SCTP reference implementation is free software;
	12	* you can redistribute it and/or modify it under the terms of
	13	* the GNU General Public License as published by
	14	* the Free Software Foundation; either version 2, or (at your option)
	15	* any later version.
	16	*
	17	* The SCTP reference implementation is distributed in the hope that it
	18	* will be useful, but WITHOUT ANY WARRANTY; without even the implied
	19	* ************************
	20	* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
	21	* See the GNU General Public License for more details.
	22	*
	23	* You should have received a copy of the GNU General Public License
	24	* along with GNU CC; see the file COPYING. If not, write to
	25	* the Free Software Foundation, 59 Temple Place - Suite 330,
	26	* Boston, MA 02111-1307, USA.
	27	*
	28	* Please send any bug reports or fixes you make to the
	29	* email address(es):
	30	* lksctp developers <[email protected]>
	31	*
	32	* Or submit a bug report through the following website:
	33	* http://www.sf.net/projects/lksctp
	34	*
	35	* Written or modified by:
	36	* La Monte H.P. Yarroll <[email protected]>
	37	* Jon Grimm <[email protected]>
	38	* Karl Knutson <[email protected]>
	39	* Sridhar Samudrala <[email protected]>
	40	*
	41	* Any bugs reported given to us we will try to fix... any fixes shared will
	42	* be incorporated into the next SCTP release.
	43	*/
	44
	45	#include <linux/types.h>
	46	#include <net/sctp/sctp.h>
	47	#include <net/sctp/sm.h>
	48
	49	static void sctp_tsnmap_update(struct sctp_tsnmap *map);
	50	static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
	51	__u16 len, __u16 base,
	52	int started, __u16 start,
	53	int ended, __u16 end);
	54
	55	/* Initialize a block of memory as a tsnmap. */
	56	struct sctp_tsnmap sctp_tsnmap_init(struct sctp_tsnmap map, __u16 len,
	57	__u32 initial_tsn)
	58	{
	59	map->tsn_map = map->raw_map;
	60	map->overflow_map = map->tsn_map + len;
	61	map->len = len;
	62
	63	/* Clear out a TSN ack status. */
	64	memset(map->tsn_map, 0x00, map->len + map->len);
65
66	/* Keep track of TSNs represented by tsn_map. */
67	map->base_tsn = initial_tsn;
68	map->overflow_tsn = initial_tsn + map->len;
69	map->cumulative_tsn_ack_point = initial_tsn - 1;
70	map->max_tsn_seen = map->cumulative_tsn_ack_point;
71	map->malloced = 0;
72	map->num_dup_tsns = 0;
73
74	return map;
75	}
76
77	/* Test the tracking state of this TSN.
78	* Returns:
79	* 0 if the TSN has not yet been seen
80	* >0 if the TSN has been seen (duplicate)
81	* <0 if the TSN is invalid (too large to track)
82	*/
83	int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
84	{
85	__s32 gap;
86	int dup;
87
88	/* Calculate the index into the mapping arrays. */
89	gap = tsn - map->base_tsn;
90
91	/* Verify that we can hold this TSN. */
92	if (gap >= (/* base / map->len + / overflow */ map->len)) {
93	dup = -1;
94	goto out;
95	}
96
97	/* Honk if we've already seen this TSN.
98	* We have three cases:
99	* 1. The TSN is ancient or belongs to a previous tsn_map.
100	* 2. The TSN is already marked in the tsn_map.
101	* 3. The TSN is already marked in the tsn_map_overflow.
102	*/
103	if (gap < 0 \|\|
104	(gap < map->len && map->tsn_map[gap]) \|\|
105	(gap >= map->len && map->overflow_map[gap - map->len]))
106	dup = 1;
107	else
108	dup = 0;
109
110	out:
111	return dup;
112	}
113
114
115	/* Mark this TSN as seen. */
116	void sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
117	{
118	__s32 gap;
119
120	/* Vacuously mark any TSN which precedes the map base or
121	* exceeds the end of the map.
122	*/
123	if (TSN_lt(tsn, map->base_tsn))
124	return;
125	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
126	return;
127
128	/* Bump the max. */
129	if (TSN_lt(map->max_tsn_seen, tsn))
130	map->max_tsn_seen = tsn;
131
132	/* Assert: TSN is in range. */
133	gap = tsn - map->base_tsn;
134
135	/* Mark the TSN as received. */
136	if (gap < map->len)
137	map->tsn_map[gap]++;
138	else
139	map->overflow_map[gap - map->len]++;
140
141	/* Go fixup any internal TSN mapping variables including
142	* cumulative_tsn_ack_point.
143	*/
144	sctp_tsnmap_update(map);
145	}
146
147
148	/* Initialize a Gap Ack Block iterator from memory being provided. */
149	SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
150	struct sctp_tsnmap_iter *iter)
151	{
152	/* Only start looking one past the Cumulative TSN Ack Point. */
153	iter->start = map->cumulative_tsn_ack_point + 1;
154	}
155
156	/* Get the next Gap Ack Blocks. Returns 0 if there was not another block
157	* to get.
158	*/
159	SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
160	struct sctp_tsnmap_iter *iter,
161	__u16 start, __u16 end)
162	{
163	int started, ended;
164	__u16 _start, _end, offset;
165
166	/* We haven't found a gap yet. */
167	started = ended = 0;
168
169	/* If there are no more gap acks possible, get out fast. */
170	if (TSN_lte(map->max_tsn_seen, iter->start))
171	return 0;
172
173	/* Search the first mapping array. */
174	if (iter->start - map->base_tsn < map->len) {
175
176	offset = iter->start - map->base_tsn;
177	sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 0,
178	&started, &_start, &ended, &_end);
179	}
180
181	/* Do we need to check the overflow map? */
182	if (!ended) {
183	/* Fix up where we'd like to start searching in the
184	* overflow map.
185	*/
186	if (iter->start - map->base_tsn < map->len)
187	offset = 0;
188	else
189	offset = iter->start - map->base_tsn - map->len;
190
191	/* Search the overflow map. */
192	sctp_tsnmap_find_gap_ack(map->overflow_map,
193	offset,
194	map->len,
195	map->len,
196	&started, &_start,
197	&ended, &_end);
198	}
199
200	/* The Gap Ack Block happens to end at the end of the
201	* overflow map.
202	*/
203	if (started && !ended) {
204	ended++;
205	_end = map->len + map->len - 1;
206	}
207
208	/* If we found a Gap Ack Block, return the start and end and
209	* bump the iterator forward.
210	*/
211	if (ended) {
212	/* Fix up the start and end based on the
213	* Cumulative TSN Ack offset into the map.
214	*/
215	int gap = map->cumulative_tsn_ack_point -
216	map->base_tsn;
217
218	*start = _start - gap;
219	*end = _end - gap;
220
221	/* Move the iterator forward. */
222	iter->start = map->cumulative_tsn_ack_point + *end + 1;
223	}
224
225	return ended;
226	}
227
228	/* Mark this and any lower TSN as seen. */
229	void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
230	{
231	__s32 gap;
232
233	/* Vacuously mark any TSN which precedes the map base or
234	* exceeds the end of the map.
235	*/
236	if (TSN_lt(tsn, map->base_tsn))
237	return;
238	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
239	return;
240
241	/* Bump the max. */
242	if (TSN_lt(map->max_tsn_seen, tsn))
243	map->max_tsn_seen = tsn;
244
245	/* Assert: TSN is in range. */
246	gap = tsn - map->base_tsn + 1;
247
248	/* Mark the TSNs as received. */
249	if (gap <= map->len)
250	memset(map->tsn_map, 0x01, gap);
251	else {
252	memset(map->tsn_map, 0x01, map->len);
253	memset(map->overflow_map, 0x01, (gap - map->len));
254	}
255
256	/* Go fixup any internal TSN mapping variables including
257	* cumulative_tsn_ack_point.
258	*/
259	sctp_tsnmap_update(map);
260	}
261
262	/********************************************************************
263	* 2nd Level Abstractions
264	********************************************************************/
265
266	/* This private helper function updates the tsnmap buffers and
267	* the Cumulative TSN Ack Point.
268	*/
269	static void sctp_tsnmap_update(struct sctp_tsnmap *map)
270	{
271	__u32 ctsn;
272
273	ctsn = map->cumulative_tsn_ack_point;
274	do {
275	ctsn++;
276	if (ctsn == map->overflow_tsn) {
277	/* Now tsn_map must have been all '1's,
278	* so we swap the map and check the overflow table
279	*/
280	__u8 *tmp = map->tsn_map;
281	memset(tmp, 0, map->len);
282	map->tsn_map = map->overflow_map;
283	map->overflow_map = tmp;
284
285	/* Update the tsn_map boundaries. */
286	map->base_tsn += map->len;
287	map->overflow_tsn += map->len;
288	}
289	} while (map->tsn_map[ctsn - map->base_tsn]);
290
291	map->cumulative_tsn_ack_point = ctsn - 1; /* Back up one. */
292	}
293
294	/* How many data chunks are we missing from our peer?
295	*/
296	__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
297	{
298	__u32 cum_tsn = map->cumulative_tsn_ack_point;
299	__u32 max_tsn = map->max_tsn_seen;
300	__u32 base_tsn = map->base_tsn;
301	__u16 pending_data;
302	__s32 gap, start, end, i;
303
304	pending_data = max_tsn - cum_tsn;
305	gap = max_tsn - base_tsn;
306
307	if (gap <= 0 \|\| gap >= (map->len + map->len))
308	goto out;
309
310	start = ((cum_tsn >= base_tsn) ? (cum_tsn - base_tsn + 1) : 0);
311	end = ((gap > map->len ) ? map->len : gap + 1);
312
313	for (i = start; i < end; i++) {
314	if (map->tsn_map[i])
315	pending_data--;
316	}
317
318	if (gap >= map->len) {
319	start = 0;
320	end = gap - map->len + 1;
321	for (i = start; i < end; i++) {
322	if (map->overflow_map[i])
323	pending_data--;
324	}
325	}
326
327	out:
328	return pending_data;
329	}
330
331	/* This is a private helper for finding Gap Ack Blocks. It searches a
332	* single array for the start and end of a Gap Ack Block.
333	*
334	* The flags "started" and "ended" tell is if we found the beginning
335	* or (respectively) the end of a Gap Ack Block.
336	*/
337	static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
338	__u16 len, __u16 base,
339	int started, __u16 start,
340	int ended, __u16 end)
341	{
342	int i = off;
343
344	/* Look through the entire array, but break out
345	* early if we have found the end of the Gap Ack Block.
346	*/
347
348	/* Also, stop looking past the maximum TSN seen. */
349
350	/* Look for the start. */
351	if (!(*started)) {
352	for (; i < len; i++) {
353	if (map[i]) {
354	(*started)++;
355	*start = base + i;
356	break;
357	}
358	}
359	}
360
361	/* Look for the end. */
362	if (*started) {
363	/* We have found the start, let's find the
364	* end. If we find the end, break out.
365	*/
366	for (; i < len; i++) {
367	if (!map[i]) {
368	(*ended)++;
369	*end = base + i - 1;
370	break;
371	}
372	}
373	}
374	}
375
376	/* Renege that we have seen a TSN. */
377	void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
378	{
379	__s32 gap;
380
381	if (TSN_lt(tsn, map->base_tsn))
382	return;
383	if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
384	return;
385
386	/* Assert: TSN is in range. */
387	gap = tsn - map->base_tsn;
388
389	/* Pretend we never saw the TSN. */
390	if (gap < map->len)
391	map->tsn_map[gap] = 0;
392	else
393	map->overflow_map[gap - map->len] = 0;
394	}
395
396	/* How many gap ack blocks do we have recorded? */
397	__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map)
398	{
399	struct sctp_tsnmap_iter iter;
400	int gabs = 0;
401
402	/* Refresh the gap ack information. */
403	if (sctp_tsnmap_has_gap(map)) {
404	sctp_tsnmap_iter_init(map, &iter);
405	while (sctp_tsnmap_next_gap_ack(map, &iter,
406	&map->gabs[gabs].start,
407	&map->gabs[gabs].end)) {
408
409	map->gabs[gabs].start = htons(map->gabs[gabs].start);
410	map->gabs[gabs].end = htons(map->gabs[gabs].end);
411	gabs++;
412	if (gabs >= SCTP_MAX_GABS)
413	break;
414	}
415	}
416	return gabs;
417	}